Today, as display means for use in different types of electric appliances such as television sets, PDAs (personal digital/data assistant) and mobile telephones, liquid crystal displays are widely used for their light weight, slimness, and low power consumption; especially widely used are transmissive liquid crystal displays that are illuminated from behind to offer improved viewability of what is displayed thereon.
To achieve improved viewability and display quality in transmissive liquid crystal displays, illumination light from a backlight needs to be evenly guided to the display panel to reach all corners thereof so that even surface emission from all over the display panel is achieved with reduced unevenness in light amount.
To that end, in conventional transmissive liquid crystal displays, light guides (such as reflective plates and light guide plates) are constantly being improved; in addition, with the trend toward increasingly large-screen display panels, it is becoming common to illuminate a display panel with a plurality of backlights.
According to one conventionally disclosed and proposed technology (for example, see patent document 1 listed below) related to the present invention, a display panel is divided into predetermined areas, and the hue and brightness in each area are detected for automatic adjustment.
As other conventional technologies related to the present invention, there are disclosed and proposed various light-emitting diode driving apparatuses and lighting apparatuses (for example, see patent documents 2 and 3 listed below) that keep constant the amount of light emitted from a light-emitting diode by use of a photosensor.    Patent document 1: JP-A-H08-313879    Patent document 2: JP-A-H05-327450    Patent document 3: JP-A-2003-163090